Apparatus for grinding a cabochon or the like

ABSTRACT

An apparatus for moving a gem stone, or other object, in a controlled circular or elliptical path with respect to a grinding wheel or cutting tool, for example for grinding a cabochon. It comprises a rotatable assembly to which the stone or the like is attached. The assembly contains a stem-like driver having a tongue reciprocable in a transverse guide. Also forming part of the assembly and rotating with it, is a part formed with an elongate cam slot disposed at right angles to the transverse guide and engaged by a stationary circular cam. The stem-like driver rotates in a normally stationary sleeve, the position of which is adjustable to predetermine the degree of elliptical movement generated. Provision is made not only to adjust the assembly with respect to the grinding or cutting tool, but also angularly in order to dispose the stone or the like in an inclined position with respect to the grinding wheel for chamfering.

Reed

[ Oct. 29, 1974 APPARATUS FOR GRINDING A CABOCHON OR THE LIKE [76]Inventor: Glen H. Reed, 2536 Torisdale Ct.,

Toledo, Ohio 43611 [22] Filed: July 9, 1973 [21] Appl. No.2 377,636

[52] US. Cl. 511/127, 51/229 [51] Int. Cl 1324b 17/02 [58] Field ofSearch 51/100 R, 101 R, 101 LG,

[56] References Cited UNITED STATES PATENTS 2,350,234 5/1944 Horton51/101 R X 2,724,220 11/1955 Shaw 51/229 X Primary Examiner-A1 LawrenceSmith Assistant Examiner-Nicholas P. Godici Attorney, Agent, orFirmMalcolm W. Fraser [57] ABSTRACT An apparatus for moving a gem stone,or other object, in a controlled circular or elliptical path withrespect to a grinding wheel or cutting tool, for example for grinding acabochon. It comprises a rotatable assembly to which the stone or thelike is attached. The assembly contains a stem-like driver having atongue reciprocable in a transverse guide. Also forming part of theassembly and rotating with it, is a part formed with an elongate camslot disposed at right angles to the transverse guide and engaged by astationary circular cam. The stem-like driver rotates in a normallystationary sleeve, the position of which is adjustable to predeterminethe degree of elliptical movement generated. Provision is made not onlyto adjust the assembly with respect to the grinding or cutting tool, butalso angularly in order to dispose the stone or the like in an inclinedposition with respect to the grinding wheel for chamfering.

4 Claims, 7 Drawing Figures PATENTEDUBIZSIISM v v SHEEI 20F 4lllllilllllllllll l APPARATUS FUR GINDING A CABOCll-ION OR THE LIKEBACKGROUND AND SUMMARY OF THE INVENTION I Most apparatus available forgenerating ellipses are expensive and complicated. It is a desideratumto provide an apparatus of this character which is not only relativelysimple and inexpensive, but can be adjusted to produce differentellipses. Although the uses are wide and varied, a large demand existsin the field of grinding cabochons. Many amateurs and professionalsworking in the lapidary art have a need for a reliable apparatus of thischaracter, which is simple to operate.

The apparatus according to this invention has relatively few parts, andthese include a subassembly to which the stone or the like is attached,and which is carried through a path of circular or elliptical form asdesired. An operating knob is turned by hand and this motion istransmitted to the subassembly which, through cam elements, travelselliptically as regulated by a simple adjuster plate, the position ofwhich determines whether a round stone or an elliptical stone is to beformed, and, if the latter, the particular elliptical shape desired. Asa consequence, all that is required is first to attach the stone in amanner well known in the art, position the adjuster plate in accordancewith the shape of stone desired, and then manually turn the operatingknob so that the stone will be appropriately turned against the rotatinggrinder wheel. The only other adjustment necessary is from time to timeto advance the stone to the grinder wheel which can be done manually ina very simple manner. In the event it is desired to chamfer the stone,the assembly is tilted to the proper angle and the stone will be movedthrough the correct path as above indicated.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a fragmentary frontperspective view of the apparatus for grinding a cabochon in circular orelliptical form;

FIG. 2 is a vertical sectional view substantially on the line 2-2 ofFIG. 1;

FIG. 3 is a top plan view of the ellipse generating apparatus shown inFIG. 1 with the grinding wheel and associated frame parts removed;

FIG. 4 is a front end elevation of the apparatus showing by broken linesparts of the assembly operative for effecting elliptical movement;

FIG. 5 is a fragmentary elevation of the rear of the apparatus showingparticularly the plate for adjusting the elliptical movement generatedby the assembly;

FIG. 6 is an exploded view of parts of the subassembly by whichelliptical movement is effected; and

FIG. 7 is a perspective view of the driver which is rotated for causingthe elliptical motion.

DESCRIPTION OF THE PREFERRED EMBODIMENT The illustrated embodiment ofthe invention comprises an apparatus for grinding a cabochon, or thelike, in a circular pattern or in an elliptical path, means beingprovided to effect adjustment to handle from a round surface to arelatively long and narrow ellipse. As shown. the apparatus comprises anassembly including a driven circular metal disc 10, having on one sidean integral forwardly extending centrally disposed hub 11, formed with ahollow bore 12. Adapted to be mounted in the bore 12 is an adaptor stem13 which is retained in position by a set screw 13a. On the outer end ofthe stem is a head M, to which the element to be ground, such as afacitious stone E, is attached. The attachment can take place in anysuitable manner, but it is usual to attach the stone by hot glue,affording a secure bond but one which enables easy removal of the stone.Although, throughout the description, reference will be made to a stone,such as a cabochon, to be ground by a grinding wheel G, it is to beunderstood that the invention is not so limited and has utility for manyother uses. It will hereinafter appear that the stone E can be rotatedto grind a circular stone, or it can be revolved through an ellipticalpath to grind an ellipse of predetermined form.

The driven circular disc 10 forms part of an assembly. As shown, it isformed on the inner face with a circular recess 15 concentric to thehollow bore 12. The recess 15 has a flat bottom 16 and passingtransversely through the bore 12, and extending from side to side of therecess, is a guide groove 17. Slideable in the groove 17 is anapproximately rectangular driving tang or tongue 18, which is integralwith a cricular washer 20 forming part of an elongate driver stem 21.The circular washer 20 is approximately of a thickness corresponding tothe depth of the recess 15. The outer end portion of the stem isprovided with a flat surface 22, and adjacent thereto are screw threads19. Fitting over the outer end of the stem is a knurled operating knob23 which contains a set screw 24 engaging the flat surface 22 so thatthe knob can rotate the driver stem 21. On the threaded portion 19 arelock nuts 25 to insure the retention of the knob in position.

Fitting flatly against the circular driven disc 10 and retaining thetang 18 in the guide groove 17 is a circular metal cover plate 26 whichhas an elongate slot 27 aligned with the guide groove 17 to enable thedriver stem 21 to slide in one direction or another along the guidegroove 17 in the operation of the apparatus. Abutting flatly against thecover plate 26 and forming part of the assembly is an inner circular,metal guide plate 28 of approximately the same diameter as that of thecover plate 26 and disc 10, and this plate is provided with a relativelylarge elongate cam slot 29 which is rounded at opposite ends, and isdisposed perpendicularly to the guide groove 17 and slot 27.

The disc 10, cover plate 26, and inner guide plate 28 are securedtogether to form a rigid assembly in the relative positions shown onFIG. 6, by two oppositely disposed screws 30 extending through holes inthe plate 26 and cover plate 26 and are threaded into holes in the disc10. This assembly also includes the driver stem 21 with a tang 18 insliding engagement with the guide groove 17., and held in position bythe integral washer 20 which is engaged on its outer face by the innerface of the cover plate 26.

Operating in the cam slot 29 is a circular stationary metal cam plate ordisc 31 which is secured to an upright support plate 32 by a pair ofscrews 33. The cam disc 31 is of a dimension that the assembly,including the guide plate 28, can move slidably from end to end of theslot 29, and revolve about it. The screws 33 are arranged on oppositesides of a cut-out, or aperture 33 (FIGS. 2 and 5). The cam disc 31 isformed with an elongate slot 35 generally aligned with the slot 27 ofthe cover plate 26. The driver stem 21 extends freely through the slots27 and 35, and rotates in a sleeve 36 (FIGS. 2 and 3), which is rigidwith and connected to an adjuster plate 37 which is shiftable foradjustment purposes on the support plate 32. The diameter of the driverstem 21 is slightly less than narrow dimension of the slots 27 and 35 inorder to contact the sides thereof and move freely along same. In theplate 37 are curved slots 38 at opposite ends to receive rigid boltsprojecting from the support plate 32, and between the slots 38 is astraight up and down slot 38' which rides over a pin 38" on the supportplate. Wing nuts 39 on the bolts enable the adjuster plate 37 to berocked to a desired position and secured in place. Such movement shiftsthe driver stem 21 to one position or another in an up and downdirection with respect to the slots 35 and the guide groove 17, therebyto adjust the apparatus for moving the stone E in a circular path or ina predetermined elliptical path. As shown, the adjuster plate 37 has apointer 40 which can be moved along a series of calibration 41indicative of certain ellipses.

In order to operate the apparatus, the control knob 23 at the back isrotated to actuate the driver stem 21. The stem rotates in a stationarysleeve 36. The turning of the driver stem 21 drives the assemblyconsisting of the discs 10, 26 and 28, through the tongue 18. Movementof this assembly, however, is governed by the stationary cam disc 31. 1fthe stem 21 is on dead center, then a rotary circular motion is impartedto the assembly, and, hence to the stone E. However, by adjustment ofthe adjuster plate 37 to effect movement from dead center of thestationary bearing sleeve 36, elliptical movement is imparted to theassembly with the cam slot 29 moving about the stationary cam disc 31,the tongue 18 moving accordingly in the guide slot 17. The greater theadjustment of the adjuster plate with relation to the calibrations 41,the greater will be the generated ellipse.

The support plate 32 on which the above described assembly is supportedis adjustable vertically relative to a mounting plate 42 in order toadjust the stone E toward or away from the grinding wheel G. Connectingbrackets 43 and 44 on the support plates 32 and 42, respectively, carrya vertical adjusting screw rod 45. The screw rod 45 has an operatinghandle 46 which, when it is turned, is effective to achieve the desiredvertical adjusting movement. It will be noted that the assembly carryingthe stone E projects through an enlarged opening 42' in the supportplate 42, which affords ample space to accommodate the assembly and theadjustments. A slide way for the plate 32 is provided by a pair of guidestrips 47 on opposite sides and this enables guided adjusting movement.

The mounting plate 42 has on opposite sides angle brackets 48 which areconnected to any suitable rigid support S by horizontal bolt and nutassemblies 49. By loosening these bolt and nut assemblies, the entireassembly can be tilted. The stone E can thus be properly positioned forchamfering operations. I

What 1 claim is:

1. Apparatus for grinding a cabochon or the like to a circular orelliptical shape comprising a stonecarrying assembly including a drivenmember having a transverse rectilinear guide, a driver stem having apart movable in said guide, a second driven member fixed to and movablewith said first driven member and having an elongate cam guideperpendicular to said transverse guide, a stationary cam engaged by saidcam guide to effect predetermined movement of said cam guide uponturning movement thereof, said driver stem extending freely through saidsecond driven member and said cam, a stationary sleeve bearing for saiddriver stem, a handle for turning said driver stem, means for adjustingthe position of said stationary sleeve relative to said assembly forcausing the latter to travel circularly or elliptically, and saidadjusting means comprises an adjuster plate on which said stationarysleeve is rigidly mounted, and means for shifting said adjuster platefor altering the position of said driver stem relative to said assembly.

2. Apparatus as claimed in claim 1, in which said adjuster plateshifting means operates to move said driver stem laterally of the axisthereof.

3. Apparatus for grinding a cabochon or the like to a circular orelliptical shape comprising a stonecarrying assembly including a drivenmember having a transverse rectilinear guide, a driver stem having apart movable in said guide, a second driven member fixed to and movablewith said first driven member and having an elongate cam guideperpendicular to said transverse guide, a stationary cam engaged by saidcam guide to effect predetermined movement of said cam guide uponturning movement thereof, said driver stem extending freely through saidsecond driven member and said cam, a stationary sleeve bearing for saiddriver stem, a handle for turning said driver stem, a cover plateinterposed between said first and second driven members and having anelongate slot aligned with said rectilinear guide, and means forsecuring together said driven members and cover plate so as to turn as aunit.

4. Apparatus for grinding a cabochon or the like to a circular orelliptical shape comprising a stonecarrying assembly including a drivenmember having a transverse rectilinear guide, said driven membercomprises a metal plate having a recess provided with a rectilineargroove, and a tongue rigid with said driver stem and slidably engaged insaid groove, a driver stem having a part movable in said guide, acircular washer rigid with said driver stem and to which said tongue issecured, said washer being of a thickness approximately equal to thedepth of said plate recess, a second driven member fixed to and movablewith said first driven member and having an elongate cam guideperpendicular to said transverse guide, a stationary cam engaged by saidcam guide to effect predetermined movement of said cam guide uponturning movement thereof, said driver stem extending freely through saidsecond driven member and said cam, a stationary sleeve bearing for saiddriver stem, and a handle for turning said driver stem.

1. Apparatus for grinding a cabochon or the like to a circular orelliptical shape comprising a stone-carrying assembly including a drivenmember having a transverse rectilinear guide, a driver stem having apart movable in said guide, a second driven member fixed to and movablewith said first driven member and having an elongate cam guideperpendicular to said transverse guide, a stationary cam engaged by saidcam guide to effect predetermined movement of said cam guide uponturning movement thereof, said driver stem extending freely through saidsecond driven member and said cam, a stationary sleeve bearing for saiddriver stem, a handle for turning said driver stem, means for adjustingthe position of said stationary sleeve relative to said assembly forcausing the latter to travel circularly or ellipticalLy, and saidadjusting means comprises an adjuster plate on which said stationarysleeve is rigidly mounted, and means for shifting said adjuster platefor altering the position of said driver stem relative to said assembly.2. Apparatus as claimed in claim 1, in which said adjuster plateshifting means operates to move said driver stem laterally of the axisthereof.
 3. Apparatus for grinding a cabochon or the like to a circularor elliptical shape comprising a stone-carrying assembly including adriven member having a transverse rectilinear guide, a driver stemhaving a part movable in said guide, a second driven member fixed to andmovable with said first driven member and having an elongate cam guideperpendicular to said transverse guide, a stationary cam engaged by saidcam guide to effect predetermined movement of said cam guide uponturning movement thereof, said driver stem extending freely through saidsecond driven member and said cam, a stationary sleeve bearing for saiddriver stem, a handle for turning said driver stem, a cover plateinterposed between said first and second driven members and having anelongate slot aligned with said rectilinear guide, and means forsecuring together said driven members and cover plate so as to turn as aunit.
 4. Apparatus for grinding a cabochon or the like to a circular orelliptical shape comprising a stone-carrying assembly including a drivenmember having a transverse rectilinear guide, said driven membercomprises a metal plate having a recess provided with a rectilineargroove, and a tongue rigid with said driver stem and slidably engaged insaid groove, a driver stem having a part movable in said guide, acircular washer rigid with said driver stem and to which said tongue issecured, said washer being of a thickness approximately equal to thedepth of said plate recess, a second driven member fixed to and movablewith said first driven member and having an elongate cam guideperpendicular to said transverse guide, a stationary cam engaged by saidcam guide to effect predetermined movement of said cam guide uponturning movement thereof, said driver stem extending freely through saidsecond driven member and said cam, a stationary sleeve bearing for saiddriver stem, and a handle for turning said driver stem.